Rotary expansible drill bits



United States Patent 3,101,124 ROTARY EXPANSHBLE DRILL BITS Archer W. Kamrnerer, 800 N. Raymond Ave, Fullerton, Calif. Filed Apr. 19, 1960, Ser. No. 23,304 6 Claims. (ill. 175-290) The present invention relates to rotary drill bits, and more particularly to drill bits having cutters that are expandible outwardly to a greater effective drilling diameter than the inside diameter of well casing through which the bits can be lowered.

In a drill bit having cutters expandib-le outwardly by fluid pressure, the lowering of the bit through the fluid in a well bore develops pressure within the bit that tends to expand the cutters. Damage to the bit might result, or it might be difiicult or impossible to continue the descent of the bit in the well bore to the desired location. Even with expandible cutter type of drill bits in which the cutters are not expanded by fluid pressure or hydraulically, mechan ical forces might be developed during lowering of the bit in the well bore tending to expand the cutters inadvertently.

An object of the present invention is to provide a rotary drill bit having expandible cutters which are prevented from being expanded prematurely, as during lowering of the drill bit in a well bore.

Another object of the invention is to provide a rotary drill bit having cutters expandible outwardly by fluid pressure, in which the cutters are retained in retracted position against fluid pressure forces developed in the bit as a result of its being lowered through the liquid in the well bore. However, development of fluid pressure in the bit beyondna predetermined value can effect outward expan sion of the cutters. I

A further object of the invention is to provide a rotary 'drill bit having cutters expandible outwardly, in which the cutters are prevented from being inadvertently expanded by mechanical forces below a predetermined value, the

, cutters, however, being expanded outwardly when the expanding force is sufficiently great, and in which the cutters can be readily retracted to their initial position in the bit after having been expanded.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, for

the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a longitudinal sect-ion through a rotary well drilling bit disposed in a well casing, taken along the line 11 on FIG. 3, with the cutter members in retracted position;

' FIG. 2 is a view similar to FIG. 1, with the cutters in their maximum expanded position;

FIG. 3 is an enlarged cross-section taken along the line 33 on FIG. 1;

FIG. 4 isa fragmentary cross-section, on an enlarged scale, showing a retainer member for holding a cutter in its initial retracted position within a bit body;

FIG. 5 is a view similar to FIG. 4, disclosing the retainer after the cutter has been purposely expanded;

FIG. 6 is a view similar to FIG. 4 of a modified form of the invention.

As disclosed in' the drawings, a rotary expansible drill bit A is secured to the lower end of a string of drill pipe B that extends to the top of a well bore C and by means "ice of which the drill bit is lowered within a string of well casing D to a region below the casing shoe E at which a hole enlarging operation is to take place. It is to be understood that the use of the tool given herein is by way of example only, 'andthat the tool can be used for other purposes in the well bore, depending upon the specific type of cutters embodied therein. As an example, tools of the character disclosed can be used for severing a well casing and then milling away a portion thereof.

The upper portion of the rotary drill bit consists of a mandrel 10 having an upper pin 11 threadedly connected to the lower end of a string of drill pipe B. This mandrel includes an upper kelly or drill stem member 12 slidably splined to the main body 13 of the drill bit. The exterior 14 of the lower portion of the kelly is non-circular in shape, being telescopically received in a companion noncircular socket 15 in the main bit body. As an example, the kelly exterior 14 and the socket 15 may be of hexagonal shape to enable the kelly 12 to be moved longitudinal-1y relative to the body 13, while still being capable of transmitting rotary motion and torque to the body.

The mandrel 10 has a limited range of longitudinal movement within the body 13, downward movement being determined by engagement of the lower end 16 of the kelly with an inwardly directed body shoulder 17, and its upward movement being limited by engagement of an external shoulder or piston portion 18 of the kelly with a cylinder head 19 secured to the body 13. The upper end of the head has a flange 20 engaging a body shoulder 21, the flange being prevented from moving upwardly of the body by split snap retainer rings 22 fitting in a body groove 23 and overlying the flange 20. An annular guide '24 can be releasably secured to the body by a split snap ring 25 above the retainer rings 22.

The body '13 has a plurality of expansible parts mounted on it. These include cutter supporting members 26 pivotally mounted in body slots 27 on hinge pins 28 suit-ably secured to the body. Each cutter supporting member 26 depends from the hinge pin and rotatably carries a toothed roller cutter 29 at its lower end. The cutter supporting members and the cutters tend to occupy retracted positions substantially entirely within the confines of the main body 13 of the bit. The cutter supporting members 26 and the cutters 29 themselves are expandible outwardly, as when the diameter of the well bore C is to be enlarged beyond the inside diameter of the well casing D through which the drill bit can be lowered and raised. To accomplish the expansion, each cutter supporting member has an inclined expand-er surface 30 on its inner portion below the hingepin 28which tapers in an inward .and downward direction. Each expander surface terminates in a lock surface 31 formed on a lock portion 32 of the cutter supporting member. The outward expansion is accomplished by producing relative longitudinal movement between the mandrel 10 and the bit body 13, which will produce rel tive longitudinal movement between the cutter supporting members 26 and the tubular member 33 of the mandrel. This tubular member includes a lower portion 34 slidable within aguide bushing 35 mounted within a bridge 36 secured to the body and extending across the body slots 27. This guide bushing 35 is disposed below the lock portions 32 of the cutter supporting members.

Located initially substantially above the guide bushing 35 and below the hinge pins 28, and in cutter member recesses 37, is a mandrel lock and expander 38 which has outer surfaces 39 adapted to engage the expander surfaces 30 and the lock surfaces 31. The lock and expander 38 may be formed integrally with the tubular member 33, the upper end of the latter being piloted Within a socket 40 formed in the lower portion of the kelly 12. An enlarged boss 41 on the tubular member engages a downwardly facing shoulder 42 of the kel-ly, the tubular mem- 3 her 33 :being held against this shoulder -by a suitable spring retainer lock'ring 43 snapped into an internal groove 44 encompassing the kelly socket and engaging the lower end of the tubular member boss 41.

Drilling mud or other fluid can pass down through the central passage 45 in the kelly or drill stem 12 and into the central passage 46 extending completely through the tubular member 33. Leakage of fluid around the exterior of the tubular member 33 is prevented by a suitable side seal ring 47 mounted in a peripheral groove 48 in the kelly and engaging the exterior wall of the boss 41.

Assuming that the body 13 of the tool is elevated relatively along the tubular mandrel 10, the inclined expander surfaces 30 of the cutter supporting members 26 will be shifted upwardly along the lock and expander portion 3? of the tubular member 33. During such upward shifting, the cutter supporting members 26 and the cutters 29 carried thereby will be pivoted about the hinge pins 28 and urged in an outward direction. Upward movement of the body 13 with respect to the tubular mandrel 16 can continue until the cutters 29 have been shifted outwardly to their fullest extent, as determined by engagement of the stop shoulders 50 on the cutter supporting members 26 with companion shoulders 51 formed in the body on opposite sides of the slots 27. When such engagement occurs, the lower end 16 of the kelly portion of the tubular mandrel will engage the body shoulder 17 and the lock and expander 38 on the tubular member 33 will be disposed lnehind and in engagement with the lock portions 32 on the cutter supporting members 26 (FIG. 2).

The relative longitudinal movement between the tubular mandrel 19 and the body 13 of the tool is accomplished hydraulically. As shown in the drawings, the piston for enlarged portion 18 on the drill stem is received within a counterbore 52 formed in the upper portion 53 of the body of the tool, this upper portion actually constituting a cylinder having a cylindrical wall extending from a lower shoulder 54, defining the bottom of the :eounterbore, to the cylinder head 19. A confined cylinder space 55 is termed between the piston portion 18 of the kelly, the periphery of the kelly above the piston 18, and the cylinder 53, 19. A suitable packing or side seal ring as may be disposed in a suitable piston ring groove 57 in the piston 18, which is adapted to slidably seal against the cylindrical wall 54 of the cylinder. Fluid is thereby prevented from passing in a downward direction between the piston 18 and the cylinder 53. Similarly, fluid is prevented from passing in an upward direction out of the annular cylinder space 55 by an inner side seal ring 58 carried in an external groove 59 in the cylinder head 19 and slidably and sealingly engaging the periphery of the kelly 12 above the piston 18, and also by an outer side seal ring 60 disposed in an external groove 61 in the head 19 and sealingly engaging the cylinder wall 54.

Fluid under pressure in the string of drill pipe B and in the tubular mandrel passage 45 can be vfed into the 7 cylinder space 55 through one or more side ports 62 establishing communication between the central passage 45 through the kelly 12 and the cylinder space. Such, fluid under pressure is developed, in the form Olf invention disclosed in the drawings, by virtue of the fact that the passage 46 through the tubular member 33 of the mandrel is of a restricted diameter as compared to the passage 45 of the kelly portion of the mandrel. As a result, the pumping of drilling mud or other fluid at an adequate rate through the apparatus will build up a back pressure of fluid in the passage 45, which pressure will be imposed on the fluid in the cylinder space 55, acting upon the cylin der head 19 to urge the body 13 of the tool in an upward direction with respect to the tubular mandrel 10, to secure the outward expansion of the cutter supporting members 26 and cutters '29 to their fullest extent, as above described.

In addition to effecting outward expansion of the cutter supporting members 26 and the cutters 29 to their fullest extent, the fluid can pass downwardly .out of the passage 46 through the tubular member 33 and will then flow upwardly around the cutters 29 to remove the cuttings and cool the cutters themselves. The cuttings will be flushed upwardly through the annulus between the drill pipe 13 and the casing D to the top of the hole, fior appropriate disposal.

To insure the presence of adequate pressure in the cylinder space 55 in the circulation :of fluid during the hole enlarging operation, the flow of fluid through the passage 46 is further restricted by a throttle device in the tubular member itself. As shown, the lower portion of the tubular member 33 has a .counterbore 63 to receive a tubular sleeve 64, preferably made of a hard metal, such as tungsten car-bide, for the purpose of resisting erosive wear. This sleeve 64 can be secured in the lower end of the tubular member 33 in any suitable manner, as by welding. The passage through the sleeve has a smaller diameter than the passage 45.

After the rotary drill bit A has been lowered through the casing D and well bore C to the desired extent, fluid under pressure is developed in the drill pipe B and the mandrel passage 45 by pumping drilling fluid downwardly through the drill pipe and the drill bit at an appropriate rate. During such pumping action the drill pipe and drill bit are rotated. A back pressure is built up in the passages 45, as well as in the ports 62 and the cylinder space 55, which pressure acts upon the cylinder head 19 to urge the body 13, cutter supporting members 26 and cutters 29 in an upward direction with respect to the mandrel 10. During such upward movement, the expander surfaces 3h of the cutter supporting members are brought to bear against the lock and expander portion 38 of the mandrel, the cutters 29 being urged in an outward direction against the wall of the well bore C. The drill pipe B and the rotary drill bit A are rotated at the proper speed while fluid is being pumped through the apparatus, the cutters 29 beginning to cut away the wall of the well bore and being shifted outwardly as the cutting operation proceeds. While this is occurring, the hydraulic force acting upon the body 13 raises it and the cutter supporting members 26 and the cutters 29 to a further extent, until the cutters are fully expanded outwardly to the maximum extent, as determined by engagement of the supporting member top shoulders 54} with the companion stop shoulders 51 on the body, and the lower end 16 of the kelly portion 12 of'the mandrel with the body shoulder 17. With the parts in this position, the lock portions 32 of the cutter supporting members 26 bear against the lock and expander portion 38 of the tubular member 33 to preclude inadvertent partial retraction of the cutters 29 from their fully expanded position. Down- Weight can now be applied to the drill pipe B and the bit A attached thereto, the cutters bearing upon a transverse formation shoulder F therebelow produced in the well bore, the formation being drilled as a result of the rolling of the cutters 29 around the shoulder F, to enlarge the well bore.

When it is desired to retrieve the apparatus from the well bore, it is only necessary to discontinue the pumping of the drilling fluid through the drill pipe B and the drill bit A torelieve the pressure in the cylinder 53 and elevate the drill pipe B. Such elevating movement raises the tubular mandrel 10 with respect to the body 13 and the cutter supporting members 26, elevating the lock and expander portion 38 above the expander surfaces 30, whereupon the cutters 29 can drop back to their initial retracted positions, such as disclosed in FIG. 1.

During the lowering of the drill bit A through fluid in the well bore, pressure is sometimes developed in the mandrel passage 45 that is sufliciently high as to tend to elevate the body 13 of the tool along the mandrel 12, and thereby elevate the cutter supporting members 26 along the mandrel and expander 38, which tends to shift the cutters 29 outwardly against the wall of the well casing. Such expansion may resist downward movement of the cutters 29 in the well casing. In the event that a liner (not shown) is disposed in the well casing D, through which a rotary drill bit must also pass, even a relatively small expansion of the cutters 29 might prevent the tool from entering and being moved through the liner. Even .in the absence of the development of hydraulic pressures,

outward movement of the cutter supporting members 26.

and the cutters 29 themselves is prevented in a positive manner without, however, preventing expansion of the cutter supporting members and the cutters when such expension is desired.

As disclosed most clearly in FIGS. 3, 4 and 5, a re-- leasable retainer 70 is secured to the external portion of the body 13 of the tool and overlies the outer surface 71 of a cutter supporting member 26. Specifically, the re leasable retainer, which can be made of a suitable steel material, is of generally Z-shape, including an outer flange 72 that overlies and is engageable with the exterior surface 71 of a cutter supporting member. This outer flange is integral with a web 73 which is, in turn, integral with an inner flange 74 that engages the inner surface 75 of a recess '76 formed in the body 13 adjacent to a body slot 27. Opening into the recess 76 is a threaded hole 77 adapted to receive a screw 78 that passes through the inner flange 74, the head 79 of the screw abutting against the inner flange 74 and holding it against the bottom 75 of the recess. The recess has suflicient depth as to receive the inner flange 74' and the head 79 of the screw so that there are substantially no projections beyond the periphery of the body 13.

If desired, only one of the retainer members 70 can 'be provided in thedrill bit since any tendency for relative longitudinal movement to occur between the mandrel 1G and the body 13 will cause the mandrel expander retainers over the outwardly facing surfaces 71 of the supporting members 26 will prevent inadvertent outward swinging of the cutter supporting members, and will thereby preclude the cutters 29 from being expanded outwardly. Each retainer member has spring-like characteristics up to a certain point, so that even if the relative longitudinal movement between the mandrel and body 18 does result in a slight outward expansion of the cutter supporting members 26 and cutters 29, the relieving of the expanding [force will cause the retainer members 70 to reshift the cutter supporting members 26 back to their full initial retracted position within the body slots 27.

After the drill bit A has been lowered in the well bore C to the point at which the hole enlarging operation is to take place, drilling fluid can be pumped down through the string or" drill pipe B, passing through the tool passages 45, 46 and developing suflicient pressure within the mandrel and the cylinder space 55 as to elevate-the body 13 along the mandrel 10, in the manner described above. Sufficient pressure can be created to overcome the hold-- ing force of the retainer members 70, the cutter supporting members 26 moving relatively upwardly along the mandrel expander 38 -to force the cutter supporting members laterally outwardly. Such outward force will bend or deflect the outer flanges 72 of the. retainer members in an outward direction each outer flange bending to some extent with respect to its web 73 and the web The mandrel 10 then tends to telebending with respect to the inner flange 74, until the outer flange 72 is completely out of the path of movement of its associated cutter supporting member 26, such as shown in FIG. 5. For that matter, the steel of which each retainer member 70 is made may have such physical characteristics that the outer flange 72 an'd web 73 will break oif and drop into the well bore, so as not to impede expansion of the associated cutter supporting member 26 to its maximum extent.

Not only can suflicient pressure be developed Within the tool A to overcome the holding force of the retainers 70 and shift the latter to one side of the path of movement of the cutter supporting members 26, but the retainers will remain out of such pathof movement, so as not to interfere with retraction of the cutters 29 and members 26 back within the confines of the body slots 27, when the rotary drill bit is to be removed from the well bore.

By way of example, each of the retainer members 76*, which may be in the form of a spring clip, might beof such dimensions as to require about a 50 pound force on each clip 70 to'bend it out of the path of movement of its associated supporting member 26, the 50 pound force overcoming the yield point of the material of which the retainer member is made, such that it will remain in its ineffective and deformed position, such as disclosed in FIG. 5. If a greater force is desired, a plurality of retainer members 70, 70 can'be stacked one upon another,

such as disclosed in FIG. 6, in which two retainer members are secured by the screw 78 to the body 13 of the tool, there beingsuperimposed outer flanges 72, 72 overlying the outer surface 71 of a cutter supporting member 26. In the example given above, since about a 50 pound force is required to overcome the holding action of one retainer member, two spring-like clips or retainer members acting on one arm 26 would require about pounds total force to deform them out of the way, or to effect their breaking oif, whereby they are no longer effective to prevent expansion of the cutters 29 and their supporting members 26 to their fullest extent, or to prevent the refraction of the cutters 29 and their supporting members 26 completely back to their initial position.

. I claim:

1. In a rotary'well drilling bit: a body; normally re-. tracted cutter means mounted on said body for expansion laterally outwardly of said body and subsequent retraction laterally inwardly of said body; means for expanding said cutter means laterally outwardly; and a retainer for resisting outward expansion of said cutter means from its normally retracted position on said body, =said retainer including an inner flange secured'to said body, a web integral with said flange, and an outer flange integral with said web and extending transversely of said body and cutter means and overlying only partially in a transverse direction and being releasably engageable with said cutter means, said outer flange being displaced by said cutter means from the path of lateral outward movement of said cutter means when sufficient expanding force is applied to said cutter means.

2. In a rotary well drilling bit: a body; normally retracted cutter means mounted on said body for expansion laterally outwardly of said body and subsequent retraction laterally inwardly of said body; a mandrel slidably splined to said body; expander means on said mandrel engageable with said cutter means to expand said cutter means; means :for' shifting said mandrel and body longitudinally with respect to each other to shift said 2?" outer flange being displaced by said cutter means from the path of lateral outward movement of said cutter means when suflicient expanding force is applied by said expander means to said cutter means.

3. In a rotary well drilling bit: a body having a longitudinally extending slot therein; a supporting member mounted in said slot for latenal movement with respect to said body outwardly and inwardly of said body; a cutter on said supporting member; a mandrel slida'bly splined to said body; expander means on said mandrel engag iable with said supporting member to expand said supporting member and cutter; means for shifting said man- 'drel and body longitudinally with respect to each other to shift said supporting member along said expander means and expand said supporting member and cutter; and a retainer for resisting outward expansion of said supporting member and cutter from their normally retracted position on said body, said retainer including an inner flange secured to said body adjacent to said slot, a web integral with said flange, and an outer flange integral with said Web and extending transversely of said body and supporting member and overlying only partially in a transverse direction and being releasably engageable With said supporting member, said outer flange being displaced by said supporting rnember from its path of movement when suflicient expanding force is applied by said expander means to said supporting member.

4. in a rotary well drilling bit:. a body having a longitudinally extending slot therein; a supporting member mounted in said slot for lateral movement with respect to said body outwardly and inwardly of said body; a

cutter on said supporting member; a mandrel slidably splined to said body; expander means on said mandrel engageable with said supporting member to expand said supporting member and cutter; means for shitting said mandrel and body longitudinally with respect to each other to shift said supporting member along said expander means and expand said supporting member and cutter; and a retainer for resisting outward expansion of said supporting member and cutter from their normally retracted position on said body; said body having an external recess opening into a side or said slot; said retainer including an inner flange disposed in said recess and secured to said body, a web integral with said flange, and an outer flange integral with said web and overlying only partially and being releasably engageable with said supporting resisting outward expansion of said cutter means from its normally retracted position on said body, said retainer including an inner flange secured to said body, a Web integral with said flange, and an outer flange integral with said web and overlying only partially and being releasably engageable with said cutter means, said outer flange being displaced by said cutter means from the path of latenal-outward movement of said cutter means when sufficient expanding force is applied to said cutter means, said retainer being made of such material that the yield point of the material is exceeded upon displacement of the retainer by the cutter means so that the outer flange remains in its displaced position from the path oat lateral movement of "said cutter means and does not prevent subsequent retraction of said cutter means.

6. In a rotary well drilling bit: a body having 'a longitudinally extending slot therein; a supporting member mounted in said slot for lateral movement with respect to said body outwardlyiaind inwardly of said body; a cutter on said supporting member; a mandrel slidably splined to said body;exp ander means on said mandrel engagea-ble with said supporting member to expand said supporting member and cutter; means for shifting said mandrel and body longitudinally with respect to each other to shift said supporting member along said expander means and expand said supporting member and cutter; and a retainer for resisting outward expansion of said supporting member and cutter from their normally retracted position on said body, said retainer including an inner flange secured to said body adjacent to said slot, a web integral with said flange, and an outer flange integral with said web and extending transversely of said body and supporting member and overlying only partially and being releasably engageable with said supporting member, said outer flange eing displaced by said supporting member from its path of movement when suflicient expanding force is applied by said expander means to said supporting member, said retainer being made of such material that the yieldpoint of the material is exceeded upon displacement of the retainer by the supporting member so that the outer flange remains in its displaced position trom the path of lateral movement of said supporting member and does not prevent retraction of said supporting member and cutter means. Y

i References Cited in the file of this patent UNITED STATES PATENTS 1,676,569 Mitchell July 10, 1928 1,919,881 Ellis July 25 1933 2,055,648 Brack Sept. 29, 1936 2,545,036 Kammerer Mar. 31, 1951 2,546,632 Dill Mar. 27, 1951 2,719,700 Kammerer Oct. 4, 1955 2,863,641 Kammerer Dec. 9, 1958 

1. IN A ROTARY WELL DRILLING BIT: A BODY; NORMALLY RETRACTED CUTTER MEANS MOUNTED ON SAID BODY FOR EXPANSION LATERALLY OUTWARDLY OF SAID BODY AND SUBSEQUENT RETRACTION LATERALLY INWARDLY OF SAID BODY; MEANS FOR EXPANDING SAID CUTTER MEANS LATERALLY OUTWARDLY; AND A RETAINER FOR RESISTING OUTWARD EXPANSION OF SAID CUTTER MEANS FROM ITS NORMALLY RETRACTED POSITION ON SAID BODY, SAID RETAINER INCLUDING AN INNER FLANGE SECURED TO SAID BODY, A WEB INTEGRAL WITH SAID FLANGE, AND AN OUTER FLANGE INTEGRAL WITH SAID WEB AND EXTENDING TRANSVERSELY OF SAID BODY AND CUTTER MEANS AND OVERLYING ONLY PARTIALLY IN A TRANSVERSE DIRECTION AND BEING RELEASABLY ENGAGEABLE WITH SAID CUTTER MEANS, SAID OUTER FLANGE BEING DISPLACED BY SAID CUTTER MEANS FROM THE PATH OF LATERAL OUTWARD MOVEMENT OF SAID CUTTER MEANS WHEN SUFFICIENT EXPANDING FORCE IS APPLIED TO SAID CUTTER MEANS. 